Selective Reduction of the Carbonyl Group in β,γ-Unsaturated α-Ketoesters by Transfer Hydrogenation with Ru-TsDPEN

Abstract

A convenient and practical method for the selective reduction of C=O bond of a wide spectrum of α-keto β,γ-unsaturated esters via transfer hydrogenation reaction under the catalysis of Ru(p-cymene)(TsDPEN) (TsDPEN: monotosylated 1,2-diphenylethylene-1,2-diamine) was developed.

Key words

ruthenium - transfer hydrogenation - chemoselectivity - carbonyl - reduction

References

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6

The reaction process can be monitored by TLC, GC or HPLC. The unsaturated ketoester are generally consumed within 1 h. Once the starting material was consumed, the reaction can be quenched with 1 N HCl. The double bond in the product will be slowly reduced at elevated temperature (80 °C) and prolonged reaction time (10-120 h). However, it is relatively stable at r.t. under the catalysis of Ru(p-cymene) (TsDPEN), no significant amount (<1%) of 3 was detected 5 h after the consumption of the starting material.